Thermostatic device



Aug. 4 v. G. ANDERSON :rm. 2,354,655

THERMOSTA'I'IC DEVICE Filed June 27, 1941 U r u Q20 INVENTORS g "h VICTOR- G. ANDERSON 22 LEONARD'MULLER wwwz THEIR ATTORNEY Patented Aug. 1, 1944 THERMOSTATIC DEVICE Victor G. Anderson, New Rochelle, and Leonard Muller, 'Merrick, N. Y., assigrlors to Sperry Gyroscope Company, Inc., Brooklyn, N. Y., a

corporation of New York Application June 27, 1941, Serial No. 400,044

12 Claims.

This invention relates to thermostatic devices and particularly to thermal control switches for an electric "circuit by means of which the electrodes of an arclamp for searchlights may be fed or positioned. Thermostatic devices of the type herewith disclosed are especially adapted for use with searchlights or other arclights where it is necessary to maintain the light source or tip of the electrode in a desirable constant position at the focal point of the reflector for the light. Deviation of the light source from this position is indirectly utilized to obtain operation of the heat responsive or thermostatic device to con-,- trol an'energized circuit by which an electrode feeding mechanism is operated and thereby correct the position of the electrode. It is obvious, however, that this invention may be applied to control devices in other fields where the position or operation of a source of radiant heat is to be automatically controlled.

An object of the invention is to positively exert control over the position of the tip of the electrode of an arclight so as to confine its movement to predetermined limits at either side of a normal position, such as the focal point of the refiector with which it is-used.

One of the features of the invention resides in the provision of a control piece for the device constructed of a uni-metallic strip of material.

Another feature of ,the invention consists in utilization of separate window openings in the cover portion of the casing for the device for diflerentially exposing to radiant energy the respective extending arms of the thermostatically influenced movable or control element.

Other objects, features and structural details of the invention will be apparent from the following description when read in connection with the accompanying drawing, wherein,

Fig. 1 is an isometric view showing a thermostatic device constructed in accordance with the present invention, and a portion of the cover or casing enclosure for the same. 1

Fig. 2 is a diagrammatic view of the improved device illustrating the different operating positions of the contact controlling arms thereof,

- the movement being exaggerated, and

vice is indicated at 10. A pair of insulating blocks I I are suitably mounted within the casing enclosure and provide a support for the switch forming parts therein. One end of a relatively fixed element ll of the switch is secured in position between the insulating blocks II, the other end of the same having an electrical contact forming portion l3. The element I2 is also constructed of current conductive material and may be provided with an associated adjusting screw 14, suitably insulated therefrom, by means of which it is set in a desired position with relation to the movable element of the thermostatic device.

The movable element or control piece for the device is constructed of a single uni-metallic strip oi material as indicated at IS, the same having a contact forming portion l5 adapted to cooperate with the corresponding portion H of the fixed element I! to close a circuit for operating a suitable electrode feeding mechanism such as disclosed in U. S. letters Patent No. 2,023,475 to F. R. House, by means of which the position of an arclight electrode, as shown at H, in relation tothe thermostatic device, may be controlled. As shown, the movable element I5 is U-shaped, the

-\ two arms of the same, designated at I8 and I9 With reference to the drawing, a portion of v the casing encloslne and particularly the cover plate thereof for the improved thermostatic deextending in different planes from a common plane and preferably being secured to a fixed heat disseminating -member 20, preferably of greater thickness than the strip 18 or H, which is suitably mounted upon the topmost insulating block II. The arms I 8 and I9 may extend in different directions from their mutually connected free end and are respectively secured at their opposite ends in different planes, e. g., by attaching the ends to opposite faces of the fixed member 20. The movable element l5 normally asshares substantially the position shown by the full lines inFig.- 2, in which the contact l6 thereof is spaced from the contact l3 of the fixed element so that the control circuit for the suitable electrode feeding mechanism is open. The ends of the arms l8 and I9, opposite to the ends of the same fixed to member 20, are united to provide-thereat the movable contact forming portion 16 of the control piece, the position of this portionof the device beingcontrolled by the radiant heat directed upon the respective arms by the arc. When the electrode I1 is situated so that the light is focused on the portion of the easing designated at 25, stray heat and light emahating from the source aflect .the mutually opposed arms i8 and I0 substantially equally so that there is no movement of contact l6 caused thereby. As shown, the movable element is constructed of a single integral piece of uni-metallic material although obviously such may be formed by separate arms of the same material united together at their free ends. Suitably connected leads 20' and 2! from the respective fixed ends of the elements constituting the thermal control switch may be employed in connection with feed lines 22 and 23 for exerting the desired control over the operation of the electrode feed-- ing mechanism which is effected by means such as relay 3 I.

When the tip of the electrode which provides the light source for the arc lamp or searchlight is situated at the focal point of the refiector for the light or in its desired position, the light and other radiant energy therefrom passing through a lens 24 is focused upon the shield or cover plate in of the casing enclosure for the device at the position designated at 25 thereon situated to the front of the image of the electrode indicated at 26 on the cover plate. When in this position the thermal influence of the light and heat rays from the crater or thermal source ll of the positive electrode ll upon the movable element I is nil because most of the rays are blocked by the cover plate or shield ID, or at least equally distributed between legs 18 and i9, and the contacts are open, as shown in Fig. 3. As the electrode is consumed, the arc burns back from its normal position and the focused light from the electrode enters the opening or window 21 in the cover plate In situated therein in such a manner as to permit direction of the light predominantly or exclusively upon extending arm [8 of the thermostatic control piece 15. Under control of the radiant heat from the arc, the length of arm I! is extended more than arm [9 might be, so that the integral element or free end is urged in the direction shown by arrow 28, in Fig. 2, which causes closure of the respective contact portions l6 and I3 of the device and the consequent feeding of the electrode element to its desired position by means of the electrode feeding mechanism. To insure against an overfeeding movement of the electrode, the cover plate is provided with an additional opening or window 29 for the arm IQ of the thermostatic device. Expansion of the arm l9 of the control piece by means of the directed thermal infiuences effects movement of the contact l6 at the juncture of arms l8 and IS in the direction indicated by arrow 30 so that the circuit for the electrode feeding mechanism is positively opened, if such opening had not already occurred.

The defined openings 21 and 29 in the cover or shield of the casing enclosure thus providea directive means for admitting radiant heat emanating from the are at the tip of electrode,

i1 first onto arm lt and then onto arm I! so that in one instance the movable element I! of the switch closes the controlled circuit initiating operation-of the electrode feeding mechanism and in the other instance the controlled circuit is positively opened and the corrective movement interrupted without waiting until arm ll cools enough to open the switch. The movement of the arc tip effected by the electrode feeding mechanism is consequently accurately confined within predetermined limits at either side of the focal point of the reflector or other light condenser. The dual control exerted by the switch over the feeding mechanism is positively effected with-- out time delay in each instance.

It will be understood that the term uni-metallic material includes alloy metals, the term as used herewith being for the purpose of distinguishing the same from the customary bimetallic material employed in similar thermostatic devices, though it is obvious from the description that the device may remain operative even if the arms comprised materials having different coefficients of thermal expansion.

While we have described what we consider to be a highly desirable embodiment of our invention, it is obvious that many changes in form could be made without departing from the spirit of our invention, and we, therefore, do not limit ourselves to the exact form herein shown and described, nor to anything less than the whole of our invention as hereinbefore set forth, and as hereinafter claimed.

Having described our invention, what we claim and desire to secure by Letters Patent is:

1. A thermostatic device for controlling an operation comprising a first element having an electrical contact forming portion, a second element movable relatively to said first element and having a. contact forming portion adapted to co operate with the corresponding portion of the first element to close a circuit controlling said operation, said movable element being constructed of a single uni-metallic bifurcated, fiat strip of material having two arms fixed at their open ends and extending in different directions to ward the mutually connected free end of said arms.

2. A thermostatic control device for a radiant heat element comprising a control piece formed of two extending arms of the same material placed side by side but having fixed ends situated in different planes, said arms being united at their opposite ends, and a. movable control member at said union, the position of which is controlled by the radiant heat directed upon at least one of the respective arms by said element.

3. A thermostatic device for controlling operation of an electrod feeding mechanism for are lights comprising a relatively fixed element having an electrical contact forming portion, a movable element having a contact forming portion adapted to cooperate with the corresponding portion of the fixed element to close a circuit operating the electrode feeding mechanism, said movable element being constructed of a single integral U-shaped or bifurcated strip of material, the respective arms of which extend from the freely movable end in separated relation, a spacing member for securing the opposite end of said arms in spaced relation, and means for differentially exposing said respective arms to radiation from said arc as said are deviates from a normal position.

4. A thermostatic device for controlling operation of an electrode feeding mechanism for arc lights comprising, in combination, a relatively fixed element having an electrical contact forming portion, a movable element constructed of a single bifurcated uni-metallic strip of material having two flat, fixed and arms extending in different directions, a movable contact at the juncture of said arms, and a shield for the elements having a'defined open portion therein adjacent one of the arms of the movable ,element, said shield exposing at least a portion of said arm :elgiumal radiation from the arc to controlithe 5. A thermostatic device for controlling operation of an electrode feeding mechanism for are lights comprising, in combination, a relatively fixed element having an electrical contact forming portion, a movable element constructed of a single bifurcated uni-metallic strip of material having two fixed end arms extending in different directions, a movable contact at the juncture of said arms, and a shield for the elements having spaced open portions therein, one over each of the arms of the movable element whereby each arm is subject to radiant heat from the arc to cause positive movement of said contact in both directions.

6. A thermostatic device having a control piece constructed of a single uni-metallic bifurcated strip of material having extending arms having 'their open ends respectively secured to spaced portions of a fixed member, the arms of the strip being difierentially extended by the subjection of an arm to the controlled thermal influences, and a contact on the closed end of said strips moved by the resulting displacement thereof.

7. A thermostatic switch device having a control piece constructed of a single U-shaped or bifurcated, fiat uni-metallic strip of material, the respective arms of which extend from their point of juncture in difierent directions, means for securing said arms in position at, their spaced ends, the arms being differentially extended by the subjection of one or the other to controlled thermal influences, means for subjecting one arm to such thermal influences to close said switch Y device, and means for subjecting the other arm to such influences topositively open said switch device. I

8. A thermostatic arc electrode feed controlling device for are lights comprising, in combination, a switch providing a circuit controlling element for said electrode feed having two fixed end arms extending in difierent directions and a movable contact forming end at the juncture of said arms, a contact element cooperating with the contact forming end of the control element, said contact element being normally open, a

for directing rays from the arc on the other of said strips to open said contacts when the elecshield having a pair of spaced openings therein at d ifierent positions therein, one for each of the arms of the controlelement, providing directive means for admitting radiant heat emanating from the arc to said respective arms, so as to in one instance close and in the other instance positively open the circuit controlling element so that movement of the arc is confined within predetermined limits. I

9. Thermostatically controlled contact means for controlling the feed of a searchlight electrode, comprising a pair of normally open, relatively movable contacts, a pair otspaced metallic strips for positively closing and opening said contacts upon being heated sequentially by rays from the arc, means for directing rays from the are upon one of said strips to'close the contacts when the electrode has burned back so as to approach the rearwardlimiting position, and means trode is approaching its forward limiting position.

10. A thermostatic device for positioning a thermal source, said device having a moving element constructed of bifurcated sheet metal, forming two extending arms the open ends of which spread in opposite directions from a juncture to a fixed support, one arm of said sheet being differentially expanded by the greater exposure of said arm to the controlled thermal source than the other arm, whereby the juncture of said arms is moved in one direction and the other arm of said strip being expanded by the greater exposure of said other arm to said influence whereby said juncture is moved in the other direction, a control element at the juncture of said strips positively displaced in one direction or the other as one strip or the other is exposed to said thermal influence, and means controlled by displacement of saidelement in either direction for selectively displacing said source in one direction or the other.

11. A position maintaining device for maintaining an electric are within predetermined limits on either side of its normal position, comprising a two-part thermostatic element, means for causing one part to be exposed predominately to radiant energy from said are whenever said are burns back from said normal position, a contact member moved by the resultant movement of said thermostat for initiating a forward corrective movement of said arc, means for exposing a second part of said element predominately to radiant energy from said are whenever said corrective movement carries the are beyond said normal position, and means operated by the resultant movement of said element for positively moving said contact member in the opposite direction to interrupt said "corrective movement of the arc.

12. Apparatus for confining deviation of a source of radiant energy to a predetermined range of movement on opposite sides of a normal position, comprising a pair of spaced thermostatic elements, means for differentially exposing said elements to radiant energy from said source in accordance with the direction and extent of deviation of said source from its normal position, thereby to expand the element predominantly irradiated, a control device rendered operative by expansion of one element and rendered inoperative by expansion of the other element, and a source feeding mechanism controlled by said control device whereby the feed is positively started and stopped in response to the radiant heating of first one and then the other of said elements.

- VICTOR G. ANDERSON.

LEONARD MULLER. 

